Multi-physics fuel atomizer and methods

ABSTRACT

A fuel atomizer that includes a housing having a fuel inlet and at least one primary orifice positioned at the inlet, wherein the at least one orifice configured to disperse a stream of fuel into a plurality of fuel droplets. The plurality of fuel droplets contact a fuel impingement surface to break up the plurality of fuel droplets into a plurality of smaller secondary droplets and create a thin film of secondary droplets on the impingement surface. At least one pressurized air channel delivers an airflow into contact with the secondary droplets. The secondary droplets pass through a plurality of secondary outlet orifices to exit the housing. A size of the plurality of secondary droplets is reduced when passing out of the plurality of secondary orifices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 14/209,385,filed Mar. 13, 2014, now U.S. Pat. No. 9,441,580, issued Sep. 13, 2016and entitled MULTI-PHYSICS FUEL ATOMIZER AND METHODS, which is acontinuation of application Ser. No. 12/783,868, filed May 20, 2010, nowU.S. Pat. No. 8,672,234, issued Mar. 18, 2014, and entitledMULTI-PHYSICS FUEL ATOMIZER AND METHODS, the disclosures of which areincorporated, in their entireties, by this reference.

TECHNICAL FIELD

The present disclosure is directed to fuel systems, and moreparticularly directed to fuel delivery systems that use multiple stagesto enhance evaporation of the fuel.

BACKGROUND

Many types of devices have been developed over the years for the purposeof converting liquids into aerosols or fine particles readily convertedinto a gas-phase. Many such devices have been developed, for example, toprepare fuel for use in internal combustion engines. To optimize fueloxidation within an engine's combustion chamber, the fuel must bevaporized, homogenized with air, and in a chemically-stoichiometricgas-phase mixture. Ideal fuel atomization and vaporization enables morecomplete combustion and consequent lower engine out pollution.

More specifically, relative to internal combustion engines,stoichiometricity is a condition where the amount of oxygen required tocompletely burn a given amount of fuel is supplied in a homogeneousmixture resulting in optimally correct combustion with no residuesremaining from incomplete or inefficient oxidation. Ideally, the fuelshould be completely vaporized, intermixed with air, and homogenizedprior to ignition for proper oxidation. Non-vaporized fuel droplets donot ignite or combust completely in conventional internal and externalcombustion engines, which degrades fuel efficiency and increases engineout pollution.

Attempts to reduce or control emission byproducts by adjustingtemperature and pressure typically affects the NO_(x) byproduct. To meetemission standards, these residues must be dealt with, typicallyrequiring after treatment in a catalytic converter or a scrubber. Suchtreatment of these residues results in additional fuel costs to operatethe catalytic converter or scrubber and may require additional componentcosts as well as packaging and mass implications. Accordingly, anyreduction in engine out residuals resulting from incomplete combustionwould be economically and environmentally beneficial.

Aside from the problems discussed above, a fuel that is not completelyvaporized in a chemically stoichiometric air/fuel mixture causes thecombustion engine to perform at less than peak efficiency. A smallerportion of the fuel's chemical energy is converted to mechanical energywhen fuel is not completely combusted. Fuel energy is wasted andunnecessary pollution is created. Thus, by further breaking down andmore completely vaporizing the fuel-air mixture, better fuel efficiencymay be available.

Many attempts have been made to alleviate the above-described problemswith respect to fuel vaporization and incomplete fuel combustion. Inautomobile engines, for example, inlet port or direct fuel injectionhave almost universally replaced carburetion for fuel delivery. Fuelinjectors spray fuel directly into the inlet port or cylinder of theengine and are controlled electronically. Injectors facilitate moreprecise metering and control of the amount of fuel delivered to eachcylinder independently relative to carburetion. This reduces oreliminates charge transport time facilitating optimal transientoperation. Nevertheless, the fuel droplet size of a fuel injector sprayis not optimal and there is little time for the fuel to mix with airprior to ignition.

Moreover, it has been recently discovered that fuel injector sprays areaccompanied by a shockwave in the fuel spray. The shockwave may preventthe fuel from fully mixing with air. The shockwave appears to limit fuelmass to certain areas of the piston, limiting the fuel droplets' accessto air.

Other prior systems, such as heated injectors and heated fuel rails havealso been developed in attempts to remedy the problems related to fuelvaporization and incomplete fuel combustion.

SUMMARY

The principles described herein may address some of the above-describeddeficiencies and others. Specifically, some of the principles describedherein relate to liquid processor apparatuses and methods.

One aspect provides a fuel atomizer that includes a housing having afuel inlet, at least one primary fuel exit orifice, a fuel impingementsurface, at least one air, or oxidant, inlet or supply channel, and aplurality of secondary atomizer outlet orifices. At least one primaryorifice is positioned at the fuel inlet and is configured to disperse astream of fuel into a plurality of fuel droplets. The fuel impingementsurface is configured and arranged to be contacted by the plurality offuel droplets to break up the plurality of fuel droplet into a pluralityof smaller secondary droplets and create a thin film of secondary fueldroplets on the impingement surface. At least one pressurized airchannel is configured to deliver an air flow into contact with thesecondary droplets. The plurality of secondary orifices are arranged tohave the secondary droplets pass through to exit the housing. The sizeof the plurality of secondary droplets is reduced when passing throughthe plurality of secondary orifices.

At least one primary orifice positioned at the fuel inlet may bearranged coaxially with the fuel impingement surface. The plurality ofsecondary droplets may accelerate to high velocity speed when passingthrough the plurality of secondary orifices. The housing may be one of amanifold, a cylinder, a head combustion chamber, and an intake port intoa cylinder head. The fuel impingement surface may be arranged at anangle in the range of about, but not constrained or limited to, 90degrees to about 135 degrees relative to a longitudinal axis of thehousing. The plurality of secondary orifices may be arranged at an anglebetween about 0 degrees and about 90 degrees relative to a longitudinalaxis of the housing. The fuel atomizer may further comprise a fuelmetering member that defines the primary fuel inlet orifice.

Another aspect of the present disclosure relates to a method ofatomizing fuel that includes providing an atomizing device comprising atleast one primary orifice, an impingement surface, a mixing chamber, anda plurality of secondary orifices, passing a stream of fuel through theat least one primary orifice to create a plurality of first fueldroplets, and contacting the plurality of first fuel droplets againstthe impingement surface to break up the plurality of fuel droplets intoa plurality of smaller sized secondary droplets and create a thin filmof secondary droplets on the impingement surface. The method alsoincludes mixing the plurality of second droplets with a pressurized airflow to form a fuel/air mixture, passing the fuel/air mixture throughthe plurality of secondary orifices to shear the plurality of seconddroplets into a plurality of smaller sized third droplets, anddispersing the plurality of third droplets from the atomizing device.

The step of providing the atomizing device may include arranging atleast one primary fuel orifice, the impingement surface, and pluralityof secondary orifices coaxially. Mixing the plurality of second dropletswith a pressurized air flow may include delivering a flow of air in adirection that is at least partially radial. Passing the fuel/airmixture through the plurality of secondary orifices may include rapidacceleration of the fuel/air mixture to high velocity speeds. Theatomizing device may further include a fuel metering device that definesat least one primary orifice, and passing a stream of fuel through theat least one primary orifice with the fuel metering device.

A further aspect of the present disclosure relates to a pre-combustionfuel mixing device that includes a housing, a valve, a first nozzlemember, an impingement surface, a mixing chamber, a plurality of airpassages, a plurality of second orifices, and a dispersing nozzle. Thevalve is enclosed by the housing and arranged to deliver a stream offuel. The first nozzle member includes a plurality of first orifices,wherein passage of the stream of fuel through the plurality of firstorifices creates a plurality of first fuel droplets. The impingementsurface is arranged in a flow path of the plurality of first fueldroplets, wherein contacting the plurality of first fuel dropletsagainst the impingement surface breaks up the plurality of first fueldroplets into a plurality of smaller sized second droplets. Theplurality of angled air passages leads into the mixing chamber, whereina flow of pressurized air is delivered through the air passages to mixwith the plurality of second droplets to create a fuel/air mixture. Theplurality of second orifices are arranged to have the fuel air mixturepass, wherein the plurality of second droplets accelerate to highvelocity (e.g., sonic) speed when passing through the plurality ofsecond orifices to reduce a size of the plurality of second droplets toa plurality of smaller sized third droplets. The dispersing nozzlespaces apart the plurality of third droplets to permit an increasedevaporation rate of the plurality of third droplets.

At least a portion of the impingement surface may be arranged at anangle relative to a longitudinal axis of the device. The dispersingnozzle may be removably mounted to the housing or fully integrated as asingle component. The plurality of angled air passages may be arrangedat an angle relative to a longitudinal axis of the device. The pluralityof angled air passages may include a secondary angle relative to theimpingement surface, thereby forming a compound angle that induces ahelical rotation to the pressurized air flow. The plurality of secondaryorifices may be arranged at an angle relative to a longitudinal axis ofthe device.

Another aspect of the present disclosure relates to a method ofvaporizing fuel that includes providing a fuel atomizing device thatincludes a fuel metering device, an impingement surface, and a pluralityof outlet orifices, controlling a pressurized air flow to deliver airthrough the housing and out of the plurality of outlet orifices tocreate an air flow, and controlling a fuel supply to deliver a flow offuel from the fuel metering device onto the impingement surface, theflow of fuel including a plurality of first fuel droplets that break upinto smaller sized second fuel droplets upon contacting the impingementsurface. The method also includes mixing the second fuel droplets withthe air flow, moving the second fuel droplets through the plurality ofoutlet orifices, the second fuel droplets breaking up into smaller sizedthird fuel droplets upon exiting the plurality of outlet orifices,enhancing, accelerating or promoting rapid vaporization of the thirdfuel droplets as the third fuel droplets disperse from the plurality ofoutlet orifices. The method may further include controlling the fuelsource to turn OFF the flow of fuel while maintaining the air flow, andcontrolling the pressurized air source to turn OFF the air flow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate certain embodiments discussed belowand are a part of the specification.

FIG. 1 is a perspective view of an example fuel system in accordancewith the present disclosure.

FIG. 2 is an exploded perspective view of the fuel system of FIG. 1.

FIG. 3 is a side view of the fuel system of FIG. 1.

FIG. 4 is a top view of the fuel system of FIG. 1.

FIG. 5 is a front view of the fuel system of FIG. 1.

FIG. 6 is a cross-sectional side view of the fuel system of FIG. 4 takenalong cross-section indicators 4-4.

FIG. 7 is a cross-sectional top view of the fuel system of FIG. 3 takenalong cross-section indicators 3-3.

FIG. 8 is a detailed view of a portion of the fuel system of FIG. 7.

FIG. 9 is a top view of another example fuel system in accordance withthe present disclosure.

FIG. 10 is a cross-sectional side view of the fuel system of FIG. 9taken along cross-section indicators 10-10.

FIG. 11 is a detailed view of a portion of the fuel system shown in FIG.10.

FIG. 12 is a side view of another example fuel system in accordance withthe present disclosure.

FIG. 13 is a bottom view of the fuel system of FIG. 13.

FIG. 14 is a cross-sectional side view of the fuel system of FIG. 12taken along cross-section indicators 14-14.

FIG. 15 is a detailed view of a portion of the fuel system of FIG. 14.

FIG. 16 is a side view of an atomizer of the fuel system of FIG. 1.

FIG. 17 is a rear view of the atomizer of FIG. 16.

FIG. 18 is a front view of the atomizer of FIG. 16.

FIG. 19 is a cross-sectional view of the atomizer of FIG. 16 taken alongcross-section indicators 19-19.

FIG. 20 is a cross-sectional view of the atomizer of FIG. 19 taken alongcross-section indicators 20-20.

FIG. 21 demonstrates a pressurization stage of operation of the fuelsystem of FIG. 1.

FIG. 22 demonstrates further development of the pressurization stage ofFIG. 21.

FIG. 23 demonstrates a first orifice break up stage of operation of thefuel system of FIG. 1.

FIG. 24 demonstrates an impingement break up stage of operation of thefuel system of FIG. 1.

FIG. 25 demonstrates a thin film break up stage of operation of the fuelsystem of FIG. 1.

FIG. 26 demonstrates a sonic velocity break up stage of operation of thefuel system of FIG. 1.

FIG. 27 demonstrates a fuel purge stage of operation of the fuel systemof FIG. 1.

FIG. 28 demonstrates an air evacuation stage of operation of the fuelsystem of FIG. 1.

FIG. 29 illustrates an idle stage of operation of the fuel system ofFIG.

FIG. 30 is a graph showing an example air and fuel sequencing of a fuelsystem according to the present disclosure.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical elements.

DETAILED DESCRIPTION

Illustrative embodiments and aspects are described below. It will, ofcourse, be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, that will vary from oneimplementation to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

As used throughout the specification and claims, the term “droplet”refers to a small sized drop of liquid. The drop of liquid may have anyshape and volume. A droplet may include a single drop of the liquid ormultiple drops of the liquid combined together, possibly in a serialarrangement. The words “including” and “having,” as used in thespecification, including the claims, have the same meaning as the word“comprising.”

The present disclosure is directed to fuel preparation systems andmethods. However, small particle technology has benefits in manyapplications such as high altitude or low orbit applications andunderwater applications. One aspect of the present disclosure relates tothe use of multiple physics phenomena to change a liquid state fuel intoa fine particle mixture readily convertible into a gaseous state. Thechange from liquid to gas may occur in a plurality of steps that eachutilize a different physics phenomena. For example, a first step mayinclude breaking down a continuous stream of liquid fuel into aplurality of first droplets or strings of connected first droplets bypassing the stream of fuel through a single orifice or multiple orificesusing liquid energy. In this step, a fluid stream under pressure may beforced through small orifices of, for example, a controlled meteringdevice, to create initial formation of the first droplets. Single ormultiple metered streams may be employed to enhance the initialformation of the first droplets and direct the droplets toward the nextstage.

In a second step, the first droplets are broken up through mechanicalimpingement utilizing liquid energy. In this second step, the firstdroplets or strings of first droplets are impacted against an obstaclesuch as an impingement surface. This impact results in break up of thefirst droplets into smaller sized second droplets due to rapiddeceleration and considerable droplet deformation. The impingementsurface is typically positioned within an optimized distance from themetering device to facilitate the break up of first droplets intosmaller second droplets.

In a third step, the film, or droplets leaving the impingement feature,experience a high shear as they enter the surrounding air flow. Theshear causes further distortion of the droplets and further break up.

In a fourth step the third droplets are sheared by passing throughmultiple orifices utilizing gas energy. The third droplets areintroduced into an air flow within a mixing chamber to form a two-phasemixture of air and fuel droplets. The two-phase mixture is forcedthrough a secondary plurality of orifices where the third droplets arerapidly accelerated to high velocity (e.g., sonic) speed. The rapidacceleration shears and breaks up the third droplets into smaller sizedfourth droplets. Sonic speed is typically in the range of about 768 mphat room temperature or about 330 m/s at 20° C.

The system typically utilizes up to sonic gas velocities to causedroplet breakup. Sonic velocity (or sonic speed) is a function of thefluid properties and conditions. For air at standard sea-leveltemperature, pressure and humidity conditions, the sonic velocity isabout 341 m/s. For compressed air at 4 bar, 350K the sonic velocity istypically abut 375 m/s. The system may operate using a range of fluids,temperatures and pressures causing a change in the sonic velocity.However, the ratio of the actual velocity achieved to the sonic velocity(known as the Mach number) should remain relatively constant and may beup to 1.0.

In a fifth step, the fourth droplets are dispersed in a spray pattern inwhich the fourth droplets are separated from each other. The increasedseparation between fourth droplets facilitates faster vaporization dueto locally steeper vapor concentration gradients wherein there is lessinterference between vapor clouds of adjacent droplets. A pressuredifferential present as the fourth droplets are dispensed from thesystem may also tend to increase vaporization rates of the fourthdroplets.

Turning now to the figures, and in particular to FIGS. 1-8 and 16-20,one embodiment of a fuel system 10 is shown. The fuel system 10 maycomprise, for example, a base 12, a fuel metering device 14, an atomizer16, and a mounting bracket 18 (as shown in FIG. 2). The fuel system 10may provide a premixed supply of fuel and oxidant to a device such as,for example, an internal combustion engine. FIG. 1 illustrates the fuelsystem 10 in a manifold application wherein the base 12 defines at leastin part a manifold for use in a combustion engine.

The base 12 is a generally rigid structure that may be made of metal,ceramic, composite, plastic, or other materials. The base 12 may enclosea number of internal components. The base 12 may include a number ofcavities or seat features within which various components are mounted.For example, the base 12 may include an atomizer cavity 20 within whichat least a portion of the fuel metering device 14 and atomizer 16 aremounted. The base 12 may also include a dispense cavity 22 wherein theatomizer 16 dispenses a two-phase air/fuel spray. The base 12 may alsoinclude an air intake assembly 24 that provides a supply of air to theatomizer 16. The base 12 may comprise any size or shape. The base 12 maybe configured in other embodiments in the form of, for example, a baseportion of an intake port 112 (see FIGS. 9-11) or a base portion ofcylinder head 212 (see FIGS. 12-15) as described in more detail below.

Referring to FIGS. 2 and 8, the fuel metering device 14 includes a valveassembly 30 and an outlet 32 positioned at a distal end 34. A fuelmetering device 14 may be configured to provide controlled fuel flow tothe atomizer 16. The fuel metering device 14 may include at least oneorifice that provides break up of a stream of fuel into a plurality ofdroplets or strings of droplets of fuel. In some examples, the fuelmetering device 14 includes a plurality of orifices. A supply of fuel isdelivered from the fuel metering device under pressure and forcedthrough a relatively small orifice or orifices for initial formation ofdroplets. Multiple metered streams of droplets may be created as fuelexits the outlet of the fuel metering device 14. The streams of dropletsmay be directed toward another portion of the atomizer such as animpingement surface as described in further detail below.

In some embodiments, features of the fuel metering device 14 may beincluded with the atomizer 16. For example, one or more orifices used tocreate droplets from the supply of fuel controlled by the fuel meteringdevice 14 may be integrated into the atomizer 16. In other arrangements,features of the atomizer 16 may be integrated into the fuel meteringdevice 14. In some examples, the fuel metering device 14 and atomizer 16may be integrally formed or assembled as a single device.

The fuel metering device 14 may be an off-the-shelf fuel meteringdevice, fuel injector, or other readily available fuel metering orcontrol device. In at least one example, the fuel metering device 14 maybe any device that provides a controlled flow of fuel to the atomizer 16and directs that flow of fuel onto a surface of the atomizer such as animpingement surface. In one example, the fuel metering device 14 may bea bore hole injector that provides a single stream of droplets orstrings of droplets of fuel. In other examples, the fuel metering device14 provides two or more streams of droplets, a partially broken streamof fuel, or a continuous stream of fuel.

Referring now to FIGS. 2, 8 and 16-20, the atomizer 16 includes ahousing 40, a fuel metering device cavity 42, and a fuel inlet 44. Thehousing 40 is mounted within the atomizer cavity 20 of the base 12. Thehousing 40 defines the fuel metering device cavity 42, which cavity issized to receive at least a portion of the fuel metering device 14.First and second pressurized air sealing members 56, 58 may bepositioned between the housing 40 and the atomizer cavity 20. A thirdsealing member 60 may be positioned between the fuel metering device 14and the fuel metering device cavity 42 within the housing 40. The firstand second sealing members 56, 58 may be positioned on opposing sides ofan air inlet into the atomizer 16, for example, the air intake assembly24. The third sealing member 60 may provide a fluid-tight seal betweenthe housing 40 and the atomizer 16.

The atomizer 16 also includes a fuel inlet 44, an impingement surface46, a plurality of air channels 48, a mixing chamber 50, and a pluralityof secondary outlet orifices 52 in the outlet 54. A face of the outlet54 may be perpendicular to a longitudinal axis of the housing 40, or maybe arranged at a non-perpendicular angle relative to the longitudinalaxis of the housing 40 to form a conical outlet face that provides aquasi-perpendicular exit face to the secondary orifices 52. The fuelinlet 44 may be positioned in alignment with the outlet 32 of the fuelmetering device 14. The fuel inlet 44 may define a single inlet orificeor a plurality of inlet orifices through which the supply of fuelprovided by the fuel metering device 14 passes to create droplet breakup as the pressurized flow of fuel moves into the atomizer 16.

The impingement surface 46 may be arranged in alignment with the outlet32 of the fuel metering device 14 and the fuel inlet 44 of the atomizer16. In some arrangements, the impingement surface 46 is arrangedcoaxially with the outlet 32. The impingement surface 46 may have agenerally conical shape, which may further be diminished to represent aflat (i.e., planar) surface. In at least one example, the impingementsurface 46 includes a portion that is arranged at an angle 74 (see FIG.19) relative to a direction perpendicular to a longitudinal axis 72 ofthe atomizer 16. Typically the angle 74 is in the range of about 0degrees to about 60 degrees, and more preferably in the range of about 0degrees to about 30 degrees. Typically, the smaller the angle 74, thegreater amount of impact force exerted when the droplets contact theimpingement surface 46 to cause break up of the droplets. Some of thedroplets that contact the impingement surface 46 rebound off of theimpingement surface 46 into the mixing chamber 50. The greater the angle74, the greater the likelihood of deflection of the droplets from theimpingement surface 46 with less chance of break up of the dropletoccurring.

The impingement surface 46 is shown having a generally conical shapewith linear surfaces. In other arrangements, the impingement surface 46may have a contoured shape or include portions that are contoured. Insome arrangements, the impingement surface 46 may be slightly concave orrecessed.

The impingement surface may include at least one surface feature such asa plurality of protrusions, grooves, divots, or other type ofirregularity. Providing a surface feature may enhance break up of fueldroplets when contacting the impingement surface 46. The impingementsurface may be surface treated or constructed of differing material insupport of limiting any surface contour change from the resultingcontinual impingement.

The impingement surface 46 may include an extended or enhanced edge 76having overhanging, serrated or other features. Fuel droplets orportions of fuel droplets that contact the impingement surface 46 maymove along the impingement surface 46 to the edge 76 where the dropletsare further broken up at the edge 76 as the droplets move into themixing chamber 50. In some arrangements, a thin film of droplets of fuelmay collect along the impingement surface 46 and move radially outwardto the edge 76 where the droplets are broken up into smaller sizeddroplets. The creation of a thin film of fuel may occur coincidentallywith break up of droplets upon impact of the impingement surface 46 andrebounding of droplets of various sizes after contacting the impingementsurface 46.

The impingement surface 46 may have any sized or shaped construction.Any portion of the impingement surface 46 may any desired orientationrelative to the fuel metering device 14 and longitudinal axis 72 of theatomizer 16.

The pressurized air channels 48 of the atomizer 16 may be radiallyspaced apart around the impingement surface 46 to provide a flow of airto the mixing chamber 50 and areas surrounding the impingement surface46. The air channels 48 may extend to an outer periphery of the atomizer16 where a supply of pressurized air is provided via, for example, theair intake assembly 24 (see FIG. 6). The air channels 48 may be arrangedat an angle 78 relative to the longitudinal axis 72 (see FIG. 19). Theair channels 48 may have a maximum dimension D₁ (i.e. maximum diameter).The amount of air delivered to the mixing chamber 50 may be determinedat least in part by the number of air channels 48 and the dimension D₁.The angle 78 is typically in the range of about 30 degrees to about 90degrees, and more preferably in the range of about 30 to about 60degrees. The dimension D₁ is typically in the range of about 0.5 mm toabout 5 mm, and more preferably in the range of about 1 mm to about 2mm.

In addition to being arranged at an angle 78 relative to thelongitudinal axis 72, the air channels 48 may also be arranged at anangle relative to a tangent at an outer surface of the atomizer 16. Thatis to say, the air channels 48 may comprise an angle from tangentgreater than 0 degrees and less than 90 degrees, wherein 90 degrees isaligned radial or centered. This additional angled relationship of theair channels 48 may provide a compound angle fro the air channels 48 andmay assist in providing a helical rotation to the exiting air, therebygenerating swirling or vortex effect within the mixing chamber 50. Thevortex effect near the impingement surface may enhance break up, as wellas assist in enhancing evacuation of residual particles during fuelpurge, whereas the vortex effect in the annulus region may enhanceuniformity of two-phase air/fuel mixture distribution from the secondaryoutlet orifices. An example device that implements vortex chamberswithin a fuel mixing chamber is disclosed in U.S. Published PatentApplication No. 2007/0169760, which is incorporated herein in itsentirety by this reference.

The mixing chamber 50 may be defined at least in part surrounding theimpingement surface 46 radially outward from the impingement surface 46.The mixing chamber 50 may also include an area within the atomizer 16defined between the impingement surface 46 and the fuel inlet 44. Themixing chamber 50 may be a continuous chamber and may extend axiallyaway from the impingement surface 46 toward the outlet 54. The mixingchamber 50 may define a flow path for a mixture of air and fuel dropletsto travel toward the secondary orifices 52 at the outlet 54. Typically,the mixing chamber 50 is sized and arranged to provide a space withinwhich a flow of air provided through the air channels 48 may mix withfuel droplets (i.e., at least those fuel droplets that have been brokenup upon contact with the impingement surface 46) to create an air/fuelmixture.

The impingement surface 46 may be defined as a structure that extends orprotrudes into the mixing chamber 50. Alternatively, the mixing chamber50 may be defined as a space such as a cylindrical cavity or annulusthat is defined around an impingement surface and the structure thatdefines and supports the impingement surface 46. The bottom of theannulus may be planar or contoured to support enhanced fuel purge.

The secondary orifices 52 may be positioned at an outlet 54 of theatomizer 16. The secondary orifices 52 may be positioned radially andcircumferentially spaced apart. The secondary orifices 52 may eachindividually have a maximum dimension D₂ (e.g., maximum diameter) and bearranged at an angle 80 (see FIG. 19). The collective cross-sectionalarea defined by the secondary orifices 52 is typically less than thecross-sectional area of the mixing chamber 50 (e.g., cross-sectionalarea at the interface between the mixing chamber 50 and the secondaryorifices 52). Consequently, fluids under pressure located within themixing chamber 50 tend to accelerate as they move into and through thesecondary orifices 52. In at least some examples, the two-phase air/fuelmixture present in the mixing chamber 50 accelerates to high velocity(e.g., sonic) speeds while passing through the secondary orifices 52.This rapid acceleration tends to break up the fuel droplets in thefuel/air mixture to form a plurality of smaller-sized fuel droplets.Contacting the fuel droplets against the entrance into and sidewalls ofthe smaller sized secondary orifices 52 may physically break up at leastsome of the droplets of the air/fuel mixture.

The dimension D₂ is typically in the range of about 0.2 mm to about 3 mmand more preferably in the range of about 0.5 mm to about 1.5 m.Typically, the angle 80 is in the range of about 0 degrees to about 45degrees relative to the longitudinal axis 72, and more preferably in therange of about 0 degrees to about 20 degrees. The angled arrangement ofthe secondary orifices 52 tends to disperse the fuel mixture to separatethe fuel droplets as they exit the outlet 54. This dispersion of thefuel droplets creates additional separation between the droplets thatmay accelerate vaporization due to locally steeper vapor concentrationgradients available because the vapor clouds surrounding each of thedroplets have less interference with each other.

The outlet 54 of the atomizer 16 may be constructed as a separate piecethat is mounted to the housing 40 in a separate step. FIGS. 2 and 19illustrate the construction of outlet 54 as a separate piece. In otherarrangements, the outlet 54 may be integrally formed with the housing40. Typically, the outlet 54 defines at least a portion of the secondaryorifices 52. In some arrangements, the outlet 54 when formed as aseparate piece from the housing 40, can be exchanged with an outlethaving different sized and angled secondary orifices 52. Different sizedand angled secondary orifices 52 may be more useful for a given fuelbeing handled by the fuel system 10. The number of secondary orifices 52is typically in the range of about 2 to about 20, and more preferably inthe range of about 6 to about 12. The number and relative positioning ofsecondary orifices 52 may provide certain advantages in disbursing thefuel droplets.

Referring now to FIGS. 9-11, another example fuel system 100 is shown.The fuel system 100 includes a base 112 that is constructed as an intakeport to an engine cylinder head. The base 112 includes an atomizercavity 120, a dispense cavity 122, and a cylinder 126. A valve 128 andignition member 129 are exposed within the cylinder 126. Dispensed fuelfrom an atomizer 16 is delivered from the dispense cavity 122 and theninto the cylinder 126 where the fuel is ignited by the ignition memberafter piston compression 129.

Referring now to FIGS. 12-15, another example fuel system 200 is shown.Fuel system 200 is constructed as a direct injection system wherein thebase 212, which is constructed as a cylinder head, is mounted to acylinder 226. The base 212 includes an atomizer cavity 220 and adispense cavity 222. An ignition member 229 is exposed within thecylinder 226. Fuel dispensed from the atomizer 16 directly into thecylinder 226 is ignited by the ignition member 229 after pistoncompression.

Other types of fuel systems may benefit from the use of a fuel meteringdevice and atomizer as described herein. The fuel systems describedherein may be compatible with many different types of fuel such as, forexample, gasoline, diesel fuel and liquid propane. The relatively simpleconstruction of the atomizer, which implements basic physics phenomenarelated to liquid and gas energy, orifices, physical impingement,pressure differentials, vaporization, rapid acceleration, supersonicspeeds, and other considerations may promote certain advantages such as,for example, improved vaporization of fuel at lower pressures, higherfuel flow rates for a given particle size, reduced complexity in designand manufacturing thereby reducing costs, and less stringent tolerancesas compared to other systems like direct injection fuel injectors.

The use of multiple physical mechanisms to break up fuel into smallersized droplets in sequential order may assist in sequentially breakingthe droplets into smaller sizes to enhance the rate of evaporizationafter dispensing from the atomizer. The rate of evaporization of a fueldroplet increases exponentially as the diameter of the dropletdecreases. The rate of diffusion from the droplet to the liquid vaporinterface between the liquid core and vapor surrounding the fuel dropletmay be expressed by the following Equation 1:

$\begin{matrix}{m_{liquid} = {4\;\pi\;\rho\; r_{i}D_{{liquid} - {vapor}}{\ln\left\lbrack \frac{1 - Y_{{liquid},m}}{1 - Y_{{liquid},i}} \right\rbrack}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Y_(liquid,m)=Mass fraction of vapor far from the surface

Y_(liquid,i)=Mass fraction of vapor at the liquid/vapor interface

m_(liquid)=Mass transfer rate of liquid

D_(liquid-vapor)=Mass diffusivity

ρ=density of the liquid

r₁=radius of droplet

π=3.141593

Referring now to FIG. 21-29, an example method of dispensing fuel with afuel system is shown and described. The fuel system 10 is referencedthroughout FIG. 21-29. Other fuel system embodiments such as fuelsystems 100, 200 may be operated similarly.

The method is initiated by creating air pressure within the atomizer 16by turning ON an air supply while maintaining the fuel supply OFF, asshown in FIGS. 21 and 22. This step may also be referred to aspressurizing the atomizer 16. After sufficient air pressure is obtainedwithin the atomizer 16, excess air flow passes through the secondaryorifices 52 out of the outlet 54. The airflow 90 may be referenced as aplurality of arrows 90.

In a following operation step, while maintaining the airflow ON, asupply of fuel is turned ON and delivered by the fuel metering device 14into the atomizer 16. The supply of fuel is in the form of at least onestream of a plurality of fuel droplets or a string of fuel droplets thatare directed toward the impingement surface 46 as shown in FIG. 23. Uponcontacting the impingement surface, the first fuel droplets 91 arebroken up into smaller second droplets 92 as shown in FIG. 24.

A thin film of second droplets may collect on the impingement surface 46as shown in FIG. 25. Additional fracturing of the first and seconddroplets 91, 92 may occur as the thin film travels over the edge 76 ofthe impingement surface 46. The second droplets 92 mix with the airflow90 to create a two-part mixture of air and second droplets within themixing chamber 50. The fuel/air mixture moves under pressure towards thesecondary orifices 52, wherein rapid acceleration occurs to increase thespeed of the second droplets. The second droplets may reach supersonicspeeds. As the second droplets 92 pass through the secondary orifices52, the second droplets 92 are broken up into smaller sized thirddroplets 94 that are dispersed at the outlet 54 as shown in FIG. 26. Asthe third droplets 94 are dispersed from the atomizer 16, the thirddroplets may separate from each other. An vaporization rate for thethird droplets may increase as the third droplets 94 continue to reducein size.

In a further operation step, the fuel is turned OFF while the airflow ismaintained ON, as shown in FIG. 27. This step may be referred to as afuel purge as the airflow carries any remaining fuel within the atomizer16 out through the outlet 54.

In a further operation step, air is evacuated from the atomizer 16 byturning OFF the airflow while maintaining the fuel OFF as shown in FIG.28. In a final operation step, the airflow and fuel are maintained in anOFF state so that the fuel system remains idle.

FIG. 30 illustrates the sequencing of turning the airflow and fuelsupply ON and OFF relative to ignition in the cylinder of an engine(below top dead center (BTDC)). Typically, for a manifold or intake portinstallation, the air is maintained ON between about 360 degrees andabout 180 degrees BTDC while the fuel is maintained ON for a timeframebetween about 360 degrees and about 180 degrees BTDC that is less thanhow long the airflow is maintained ON and also within the range of 360degrees to 180 degrees BTDC when the air is maintained ON.

The preceding description has been presented only to illustrate anddescribe certain aspects, embodiments, and examples of the principlesclaimed below. It is not intended to be exhaustive or to limit thedescribed principles to any precise form disclosed. Many modificationsand variations are possible in light of the above disclosure. Suchmodifications are contemplated by the inventor and within the scope ofthe claims. The scope of the principles described is defined by thefollowing claims.

What is claimed is:
 1. An atomizer, comprising: a mixing chamber; afirst inlet configured to disperse a stream of first fluid into themixing chamber; an impingement surface against which the stream of firstfluid contacts, the impingement surface being arranged at an angle ofgreater than 0° and less than about 30° relative to a plane arrangedperpendicular to a longitudinal axis of the atomizer; a plurality ofchannels arranged at a radial angle in the range of about 30° to about60° and a tangential angle relative to the longitudinal axis, theplurality of channels being configured to deliver a flow of second fluidinto the mixing chamber to create a mixture of the first and secondfluids; a plurality of outlet orifices through which the mixture passesto form a spray plume.
 2. The atomizer of claim 1, wherein the flow ofsecond fluid creates a vortex within the mixing chamber.
 3. The atomizerof claim 1, wherein the mixture accelerates to sonic speed when passingthrough the plurality of outlet orifices.
 4. The atomizer of claim 1,wherein the outlet orifices are arranged at an angle between about 0°and about 90° relative to the longitudinal axis.
 5. The atomizer ofclaim 1, further comprising a first metering member that includes thefirst inlet.
 6. A method of atomizing fluid, comprising: providing anatomizing device comprising a mixing chamber, an impingement surfacepositioned within the mixing chamber, a plurality of inlet channels, andat least one outlet orifice, the impingement surface being arranged atan angle of greater than 0° and less than about 30° relative to a planearranged perpendicular to a longitudinal axis of the atomizing device;delivering a first fluid into contact with the impingement surface to atleast partially atomize the first fluid; mixing the first fluid with aflow of second fluid in the mixing chamber to form a mixture and tofurther atomize the first fluid, the flow of second fluid beingdelivered to the mixing chamber through the plurality of channels, theplurality of channels being arranged at a radial angle in the range ofabout 30° to about 60° and a tangential angle relative to thelongitudinal axis; passing the mixture through the at least one outletorifice to further atomize the first fluid.
 7. The method according toclaim 6, wherein providing the atomizing device includes arranging theimpingement surface and the at least one outlet orifice coaxially. 8.The method according to claim 6, wherein mixing the first fluid with theflow of second fluid includes delivering the second fluid into themixing chamber in a direction that is at least partially radial.
 9. Themethod according to claim 6, wherein passing the mixture through the atleast one outlet orifice includes rapid acceleration of the mixture tosonic speeds.
 10. The method according to claim 6, wherein the atomizingdevice further includes a metering device that controls delivery of thefirst fluid.
 11. The method according to claim 6, wherein the flow ofsecond fluid forms a vortex in the mixing chamber.
 12. A fluid mixingdevice, comprising: a mixing chamber; a valve arranged to deliver afirst fluid into the mixing chamber; an impingement surface positionedin the mixing chamber and arranged in a flow path of the first fluid,the impingement surface being arranged at an angle of greater than 0°and less than about 30° relative to a plane arranged perpendicular to alongitudinal axis of the device; a plurality of passages leading intothe mixing chamber through which a flow of second fluid is delivered tomix with the first fluid to create a mixture, the plurality of passagesbeing arranged at a radial angle in the range of about 30° to about 60°and a tangential angle in the range of about 0° to about 90° relative tothe longitudinal axis; a plurality of outlet orifices through which themixture passes to form a spray plume.
 13. The fluid mixing device ofclaim 12, wherein the flow of second fluid forms a vortex in the mixingchamber.
 14. The fluid mixing device of claim 12, further comprising adispersing nozzle comprising the plurality of outlet orifices, thedispersing nozzle being configured to form the spray plume.
 15. Thefluid mixing device of claim 12, wherein the plurality of outletorifices are arranged at an angle relative to the longitudinal axis. 16.A method of vaporizing fluid, comprising: providing an atomizing devicehaving a mixing chamber, an impingement surface positioned in the mixingchamber, and at least one outlet orifice, the impingement surface beingarranged at an angle of greater than 0° and less than about 30° relativeto a plane arranged perpendicular to a longitudinal axis of theatomizing device; delivering a first fluid onto the impingement surfaceto at least partially atomize the first fluid; forming a vortex flow ofa second fluid within the mixing chamber at least at a location upstreamof the impingement surface; mixing the first fluid with the vortex flowin the mixing chamber to form a mixture and further atomize the firstfluid; delivering the mixture through the at least one outlet orifice toform a spray plume and vaporize the first fluid.
 17. The methodaccording to claim 16, wherein the atomizing device further comprises aplurality of passages arranged at radial and tangential angles relativeto the longitudinal axis of the atomizing device, wherein forming thevortex flow includes delivering a flow of the second fluid through theplurality of passages and into the mixing chamber.
 18. The methodaccording to claim 17, wherein the radial angle is in the range of about30° to about 60° and the tangential angle is in the range of about 0° toabout 90° relative to the longitudinal axis.
 19. The method of claim 17,wherein the tangential angle is greater than 0° and less than about 90°relative to the longitudinal axis.